1. Field of the Invention
The present invention relates to a semiconductor device and more particularly to a semiconductor device having plural device regions and seal ring.
2. Description of Related Art
In order to protect a circuit-forming region in a semiconductor chip effectively from moisture, a protective structure referred to as a “seal ring” is provided so as to surround the semiconductor device (chip). The seal ring is formed with a wiring layer as in the circuit-forming region and a via (or contact).
Generally, however, the seal ring is electrically connected to a semiconductor substrate, so that noise that is apt to be generated in the device region of a digital circuit chip or the like is often transmitted to another device region through the seal ring, thereby causing malfunction of the elements provided in another region.
Japanese Unexamined Patent Application Publication No. 2006-147668 discloses a conventional method for suppressing such noise transmission. According to the method, a nonconducting part is provided in a seal ring forming region so that the nonconducting region blocks the conduction of a path from a logic unit, through the seal ring to an analog unit.